Hi Prashant,
Heating of Ammonium Dichromate(NH4) will produce Nitrogen gas(N2) and chromium oxide (Cr2 O3). This reaction will create a volcano like experience.
The experiment will produce an orange spark and throws the green chromium oxide crystals to the air.
The experiment is called as 'Ammonium dichromate volcano'
Hope you get it, if you have any doubts please comment in the comment box.
Thank you

Hello Prasanth, Ammonium dichromate((NH4)2Cr2O7)-orange solid colour. decomposes on heating to produce nitrogen gas, water vapor (gaseous due to the high temperature of the reaction), and solid chromium(III-oxdiation state) oxide.

Hope this helps.

Thank you.